Punching and stripping mechanism for presses



2 Sheets-Sheet 2 G. F. WALES Filed June 9, 1958 PUNCHING AND STRIPPINGMECHANISM FOR PRESSES Aug. 8; 1939.

!NVENTOR a? M 44- ATTORNEYS Patented Aug. 8, 1939 UNITED STATES PATENTOFFICE PUNCHING AND STBIPPING MECHANISM 13Claims.

This invention relates to a pimching and stripping mechanism which ismore particularly intended for use in connection with presses forpunching and stamping. sheet metal but may also Q be advantageouslyemployed in other installations.

The object of this invention is to provide a mechanism of this characterwhich is simple in construction, more durable in operation and cap- 10able of being set up accurately more easily and conveniently than hasbeen possible heretofore.

In the accompanying drawings:

Fig. 1 is a vertical transverse section of one form of punching andstripping mechanism embodying my improvements, and showing the punchingunit in its elevated inoperative position.

Fig. 2 is a vertical longitudinal section of the same taken on line 2-3,Fig. 1 and showing the punching unit in its lowered operative position.

Figs. 3, 4 and 5 are vertical sections of punching and strippingmechanism showing modified forms of this invention.

Figs. 6, 7 and 8 are fragmentary vertical sections showing diiferentmeans for retaining the punch guide and stripper on the punch holder ascompared with the construction shown in Figs. 1

Figs. 9, 10 and 11 are bottom plan views respectively of the mechanismshown in Figs. 6, 7 and 8.

Figs. 12 is a vertical section showing means for accurately forming thecompanion pilot openings on the ram or punch head and the bed or dieshoe for use in locating the punch and die units in their properrelative position on these parts.

In the following description similar characters of reference indicatelike parts in the several figures of the drawings:

Referring to Figs. 1 and 2, the numeral represents the lower stationarybed or shoe upon which the die unit is mounted and 2| the upper ram orhead which is movable vertically toward and from the bed or shoe andupon which the punch unit is mounted Upon the bed is mounted a dieholder 22 which rests on the same and is detachably secured thereto byscrews 23 passing through lugs or ears 24 on opposite sides of thisholder and entering threaded openings in the adjacent parts of the bed,as shown in Fig. 1.

In its upper side the die holder is provided with a pocket or recess 25which receives a button shaped die 26 which is seated with its undersideon the bottom of this recess and held against lateral movement thereinby engagement of the side of the die with the side wall of this recess.This holder is definitely located in a predetermined position on the bedso that the die carried thereby will be in exact alinement or registerwith the punch which cooperates therewith by forming 5 a pilot opening21 vertically in the top of the bed and is provided with a verticallocating pin or dowel 28 which is axially in line with the opening 23 inthe die and has its upper end engaging with an opening 30 in theunderside of the die holder 1 while its lower end engages with thelocating opening 21 in the bed. The slug 3| which is punched out of thesheet 32 which is being Derforated passes from the opening 29 in the diedownwardly and laterally through a chute 33 in 15 the die holder and isdischarged on one side of the latter.

The punching unit includes an upright punch, the upper part 34 in thepresent case being of comparatively large diameter and provided at its20 upper end with a laterally projecting collar, flange or head 35 whilethe lower bit or tip 36 thereof is of smaller diameter. This punch isarranged within a tubular one-piece punch holder I9 which is secured tothe ram with its upper end in en- 25 gagement with the underside of thesame by upright screws 31 passing through a flange 38 formed integrallyon the side of the punch holder and into threaded openings in theadjacent parts of the ram, as shown in Figs. 1 and 2.

The punch is held against vertical and lateral movement on the ram byclamping the marginal part of the collar or flange 35 between theunderside of the ram and an internal upwardly facing shoulder 39 formedin the upper end of the punch 35 holder. The lower part or tip of thepunch projects'below the lower end of the punch holder and passesthrough a tubular stripper and punch guide 40 which slides vertically inthe lower part of the punch holder. When the ram is elevated 40 and thepunch is in its inoperative position the stripper is projected so thatits lower end is flush with the tip of the punch, this beingaccomplished by a stripper or ejector-spring 4| arranged within thepunch holder and around the punch and bears with its upper end againstthe underside of the punch flange 35 and with its lower end against theupper end of the stripper 40. The extent of downward movement of thelatter within the punch holder under the action of the spring 4| islimited by a downwardly facing external shoulder 42 arranged on thestripper engaging with an upwardly facing internal shoulder 43 arrangedon the inner side of the punch holder.

Centering of the punch so that the same is in and punch are elevated soas to form the gap between the die and punch which receives theworkpiece and the stripper 43 is projected to its fullest extent by thespring 4|, as shown in Fig. 1. During the initial part of the downwardstroke of the ram the stripper and punch move in unison therewith untilthe lower ends of the punch and stripper engage with the upper side ofthe workpiece. Thereafter the punch continues its downward movementindependently of the stripper and punches a slug 3| out of the sheet 32forming the workpiece thereby forming a hole in the sheet, as shown inFig. 2. While the punch is thus perforating the sheet the stripper ispressing downwardly on the sheet, the tubular punch holder is movingdownwardly relative to the stripper and the spring 4| is compressedbetween the collar or flange 35 of the punch and the stripper, as shownin the last mentioned figure. During the first part of the subsequentupward movement of the ram with the punch and punch holder the stripperremains at rest on the work sheet 32 until the shoulders 42 and 43 ofthe stripper and punch holder engage one another, thereby causing thesheet of material which has been perforated to be pushed or strippedoil? from the tip of the punch and during the final part of the upwardmovement of the ram, punch and punch holder the same complete theirupward stroke in unison and leave the perforated sheet on the die.

In setting up the die and punch units preparatory to operating thepunching and stripping mechanism in the described manner the bed and dieholder are first provided respectively with the openings 27 and 33 inthe required position, and then the locating pin or dowel 23 is engagedat its lower and upper ends with said openings 21 and 33 therebyproperly locating the die 33 whose axis is vertically in line with theaxes of the pilot pin and these openings, as shown in Figs. 1 and 2. Thedie holder is then secured to the bed by means of the screws 23 passingthrough the holes in the lugs and into the bed.

For the purpose of accurately alining or locating the punch relative tothe die so that the same cooperate properly during the subsequentoperation of the press the spring 4| is removed from the punch holderand the punch guide or stripper is moved upwardly in the punch holder,thereby causing only the lower tip or hit 36 to project from the bottomof the punch holder. This bit is now inserted in the opening of the dieso that the same serves as a pilot which positively alines the punch anddie and while these parts are in this position the holes are drilled inthe ram for the reception of the locating pins 44 and the fasteningscrews 31. After this the punch holder is taken off the ram, thestripper or guide 43 is lowered in the punch holder, the spring 4| isrestored between the stripper or guide and the collar, flange or head 35of the punch and the punch holder is replaced on the ram in the properlocation by the use of the locating pins 44 and then fastened thereto bythe screws 31, thereby completing the die and punch assembly ready foroperation.

In order to permit a die and punch mounting of the character shown inFigs. 1 and 2 to be mounted on a press in which the shut height betweenthe bed and ram is less than that shown in these figures the mounting ofthe punch holder on the ram may be modified as shown in Fi 3. In thisconstruction the upper end of the punch holder 3| is arranged within arecess 41 counterbored in the underside of the ram and the upper ends ofthe punch and punch holder bear against the bottom of this recess.Between its upper and lower ends the punch holder 3| is provided with alaterally projecting flange 3" which is secured to the underside of theram by fastening screws 31 and the punch is properly located withreference to the die on the bed by a locating pin 44 engaging holes 45and 43 in the ram and the flange 3" in the same manner as that shown inFigs. 1 and 2. This method of mounting the punching unit on the ramprovides the necessary flexibility for adapting the punching unit topresses having various shut heights between the ram and bed inasmuch asit only requires the ram to be counterbored to produce a recess 41having a depth equal to the distance which the lower end of the bit ofthe punch must be arranged from the underside of the ram in order toaccommodate this punching unit.

If desired the use of separate locating pins or dowels may be avoidedand the punch may be so constructed that the same also serves as alocating pin or dowel. Such an organization is shown in Fig. 4 andconstructed as follows:

The numeral 43 represents a ring shaped abutment which is engaged on itsunderside by the stripper or ejector spring 4| and which is securedwithin the punch holder by clamping the same between the underside ofthe ram and an upwardly facing shoulder 43 in the bore of the punchholder 32. The upper part 34! of the punch is arranged within the ringshaped abutment 43 and held against vertical movement relative to theram and punch holder 32 by a flange or collar 53 arranged on the upperpart of the punch and clamped between the underside of the ram and anupwardly facing shoulder 5| in the bore of the abutment ring 48. At itsupper end the body 3 of the punch is provided with a locating pin ordowel 52 which is axially in line therewith and engages with a locatingopening or hole 53 arranged in the underside of the ram. Fastening ofthe punch holder 32 to the ram is efiected in the same manner as thatshown in Figs. 1 and 2 except that double screws are used.

The modified form of this invention shown in Fig. 5 embodies some of thefeatures shown in Figs. 1-4 and is constructed as follows:

In this construction the bed and ram are drilled and reamed at the sametime so as to form thereon alined locating holes or openings 54, 55 inthe bed and ram, respectively for properly locating the die and punchingunits in the proper relative position for insuring cooperation with eachother. Thereafter the bed is counterbored around th upper end of the bedopening 54 to form a c centric cylindrical socket or recess 56whiclz'receives the die 51 and the ram is counterbhs /i around the lowerend of the locating hole 55 to form a seat 53 in which is closely fittedthe upper end of the .punch holder 53. The punch holder is held in theseat 53 by a screw having its head 63. arranged in a counterbored recessii in the underside of the ram and engaging with a downwardly facingshoulder 32 on the side of the punch holder 33 and having its threadedshank 63 engaging a threaded opening in the bottom oi! the counterbore6|. In other respects the other structural features of this formof thepunch unit are substantially like those shown in Figs. 1-4 and thecorresponding parts are therefore identifled by the same referencecharacters and the description of their function is equally applicable.

Instead of constructing the stripper and punch guide and mounting thesame on the punch holder in the manner shown in Figs. 1-5 this may beaccomplished by the various means shown in Figs. 6-11 and constructed asfollows:

Referring to Figs. 6 and 9, the numeral 84 represents an abutment ringwhich is engaged by the lower end of the stripper spring II and whichengages with the upper end of a tubular stripper 65 surrounding thelower or bit end 66 of the punch and resting on an upwardly facingshoulder 6! in the bore of the punch holder. The stripper 65 is slidablein the lower end of the punch holder 94 and capable of moving upwardlyinto the punch holder by compressing the stripper spring 4| when thestripper engages the workpiece but the downward movement of the stripperfor stripping the workpiece from the bit of the punch is limited by anL-shaped clip having an upright arm 68 secured to the outer side of thepunch holder by a horizontal screw 69 said arm having a stop finger 10which projects inwardly from the lower end of the arm 68 and into thepath of a downwardly facing shoulder H on the side of the stripper andadapted to be engaged by the same, as shown in Fig. 6.

If desired the L-shaped clip may be secured to the punch holder by avertical screw I2 passing through the stop finger of this clip into thelower end of the punch holder, as shown in Figs. 8 and 11.

In the construction shown in Figs. 7 and 10 the downward movement of thestripper or punch guide relative to the punch holder is limited by astop screw 13 engaging with a downwardly facing shoulder 74 on the sideof the stripper 65.

When using a punch having a bit which is not round, such as the squarebit 66 shown in Figs. 9, 10 and 11 it is necessary to prevent the samefrom turning in order that it will cooperate with the correspondinglyshaped die. This may be accomplished in constructions shown in Figs. 6,9, 8 and 11 by engaging the inner end of the lower finger Ill of theretaining clip with a flat face 95 formed on the side of the stripper 65or by engaging the inner end of the screw 13 with a longitudinal slot 96in the side of the stripper 65, as shown in Figs. 7 and 10.

The use of retaining members similar to the clips 68, Ill and the screw13 also renders it possible to use different strippers to suit differentsizes of punches in the same punch holder 84.

If desired the drilling, reaming and counterboring of the bed and rampreparatory to mounting the die and punching units in proper alinementthereon may be effected in the manner shown in Fig. 12 which consists infirst drilling a locating hole 15 in the ram, then counterboring a seat16 in the underside of the ram around the lower end of the hole 15, thenplacing a pilot or locating bushing 11 with its upper end into thecounterbore l6 and engaging the lower end of this bushing with the topof the bed 20 and then passing the drill through the ram opening 15 andthe bore of the pilot bushing I1 and forming a locating opening 18 inthe bed. The counterbore may receive the upper end of the punch holderwhen the form of punch unit shown in Figs. 3 and is employed, the hole15 may be used for locating purposes when employing the punching unitshown in Fig. 4, and the hole I! in the bed may be used for locating thedie holder and when using the construction of die unit shown in Figs. 1and 2. When the punch is round the stop 10, shown in Figs. 6 and 8, onlyserves the purpose of limiting the downward movement of the stripper 65,and if it is desired, the stripper may be held against turning relativeto a round punch by a form of the stop I3, 14 which is shown in Fig. 7and engages with a longitudinal groove I14 in the outer side of therespective stripper.

When the punch is square in cross section, as shown in Figs. 9, and 11,or of other noncircular formation, then the stop I0 will not only limitthe outward movement of the stripper but also hold the stripper and thepunch against rotation by engaging the inner end of the stop with a fiatface IOI on the side of the respective stripper, as shown in Figs. 9 and11.

I claim as my invention:

1. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is secured between the underside of the ram and anupwardly facing shoulder on the punch holder, a tubular stripper movablelengthwise between the lower parts of the punch and the punch holder andlimited in its downward movement and an ejector spring arranged betweensaid punch and punch holder and operating to project said stripper andengaging its upper end with said collar.

2. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is immovably connected with said ram and punchholder, 9. tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring arranged between said punch andpunch holder and adapted to project said stripper, and an annularabutment surrounding the punch and engaged by the lower end of saidspring and bearing against the upper end of said stripper and anupwardly facing stop shoulder on said punch holder.

3. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is immovably connected with said ram and punchholder, a tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring arranged between said punch andpunch holder and adapted to project said stripper, an annular abutmentsurrounding the punch and engaged by the lower end of said spring andbearing against the upper end of said stripper and an upwardly facingstop shoulder on said punch holder, and means for limiting the downwardmovement of said stripper including a stop member secured to said punchholder and adapted to be engaged by a downwardly facing stop shoulder onsaid stripper.

4. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is immovably connected with said ram and punchholder, a tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring arranged between said punch andpunch holder and operating to move the stripper do'wnwardly, and meansfor detachably connecting the punch holder with said ram including aflange formed integrally on the punch holder, and a screw passingthrough said flange into said ram.

5. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ramand including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is immovably connected with said ram and punchholder, a tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring, arranged between said punch andpunch holder and operating to move the stripper downwardly, means fordetachably connecting the punch holder with said ram including a flangeformed integrally on the punch holder, and a screw passing through saidflange into said ram, and a locating pin engaging with openings in saidflange and ram.

6. A punching press comprising a bed and a ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch.

holder secured at its upper end to the ram, a punch arranged within thepunch holder and having its lower bit end projecting beyond the punchholder and adapted to cooperate with said die and provided at its upperendwith an integral collar which is immovably connected with said ramand punch holder, a tubular stripper slidable lengthwise between thelower parts of said punch and punch holder and limited in its downwardmovement relative thereto, an ejector spring arranged between said punchand punch holder and operating to move the stripper downwardly, a dieholder supporting said die and engaging said bed, and means fordetachably connecting the die holder and bed including a lug formedintegrally with the die holder and a fastening screw passing throughsaid lug and into said bed.

'7. A punching press comprising a bed and a ram movable one relativelyto the other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a one-piece tubular punch holder secured at itsupper end to the ram, a punch arranged within the punch holder andhaving its lower bit end projecting beyond the punch holder and adaptedto cooperate with said die and provided at its upper end with anintegral collar which is immovably connected with said ram and punchholder, a tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring arranged between said punch andpunch holderand operating to move the stripper downwardly, a die holdersupporting said die and engaging said bed, means detachably connectingsaid die holder and bed,

and means for locating said die holder on the bed consisting of alocating pin arranged .axially in line with said die and engaging withlocating holes .in said die holder and bed.

8. A punching press comprising a bed and ram one movable relatively tothe other, a die mounted on the bed, a punch adapted to cooperate "atits lower end with said die and provided at its upper end with a collarengaging with the underside of the ram, means for locating said punch onthe ram consisting of-a locating pin projecting upwardly from the punchand a locating opening in the ram which receives said pin, a holder forsaid punch secured to the ram, a stripper arranged adjacent to the lowerend of said punch, and spring means .for ejecting said stripper arrangedin the holder.

9. A punching press comprising a bed and ram one movable relatively tothe other, a die mounted on the bed, a punch adapted to cooperate'at itslower end with said die and provided at its upper end with a collarengaging with the underside of the ram, means for locating said punch onthe ram consisting of a locating pin projecting upwardly from the punchand a locating opening in the ram which receives said pin, a tubularholder surrounding the punch and secured to the ram, an abutment andretaining ring interposed between the underside of the ram and anupturned shoulder on the punch holder and provided with an upturnedshoulder engaging the underside of said collar, a tubular strippersurrounding the lower part of said punch and provided with a downwardlyturned shoulder cooperating with an upturned shoulder on the punchholder, and an ejector spring interposed between said ring and saidstripper.

10. A punching press comprising a bed and a ram movable one relativelyto the other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a tubular punch holder having its upper endarranged in a recess in the underside of the ram and provided betweenits upper and lower ends with a laterally projecting flange secured tothe underside of said ram, a punch arranged in the punch holder andadapted tocooperate with said die, a strippermovable lengthwise of thepunch, and spring ejecting means arranged in the punch holder and operating to project said stripper.

11. A punching press comprising a bed and ram movable one relatively tothe other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a tubular punch holder having its upper endarranged in a recess in the underside of the ram and provided with adownwardly facing shoulder, a screw secured to said ram and having ahead engaging the shoulder or said punch holder, a stripper movablelengthwise of the punch, and spring means arranged in the punch holderand operating to project said stripper.

12. A punching press comprising a bed and a ram movable one relativelyto the other, a die unit mounted on the bed, and a punch unit mounted onthe ram and including a tubular punch holder having its upper endarranged in a recess in the underside of the ram, means for connectingsaid punch holder with said ram, a punch arranged in the holder andadapted to cooperate with said die, a stripper movable lengthwise ofsaid punch, and spring means for projecting said stripper.

13. A punching press comprising a bed and a ram movable one relativelyto the other, a die unit mounted on the bed, and a punch unit'mounted onthe ram and including a tubular punch holder :0 secured at its upper endto the ram, a punch arranged within the punch holder and having itslower bit end projecting beyond the punch holder and adapted tocooperate with said die and provided at its upper end with anintegralcollar which is immovably connected with said ram and punchholder, a tubular stripper slidable lengthwise between the lower partsof said punch and punch holder and limited in its downward movementrelative thereto, an ejector spring arranged between said punch andpunch holder and adapted to project said stripper, an annular abutmentsurrounding the punch and engaged by the lower end of said spring andbearing against the upper end of said stripper and an upwardly facingstop shoulder on said punch holder, and means for limiting the downwardmovement of said stripper and also preventing turning of the samerelative to said punch holder.

GEORGE F. WALES.

